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WO1979000947A1 - Flow force balanced spool valve - Google Patents

Flow force balanced spool valve Download PDF

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Publication number
WO1979000947A1
WO1979000947A1 PCT/US1979/000193 US7900193W WO7900947A1 WO 1979000947 A1 WO1979000947 A1 WO 1979000947A1 US 7900193 W US7900193 W US 7900193W WO 7900947 A1 WO7900947 A1 WO 7900947A1
Authority
WO
WIPO (PCT)
Prior art keywords
slot
spool
groove
side wall
metering
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/US1979/000193
Other languages
French (fr)
Inventor
H Johnson
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Caterpillar Inc
Original Assignee
Caterpillar Tractor Co
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Caterpillar Tractor Co filed Critical Caterpillar Tractor Co
Priority to DE7979900423T priority Critical patent/DE2964586D1/en
Publication of WO1979000947A1 publication Critical patent/WO1979000947A1/en
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

Links

Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16K—VALVES; TAPS; COCKS; ACTUATING-FLOATS; DEVICES FOR VENTING OR AERATING
    • F16K11/00—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves
    • F16K11/02—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit
    • F16K11/06—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements
    • F16K11/065—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members
    • F16K11/07—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members with cylindrical slides
    • F16K11/0708—Multiple-way valves, e.g. mixing valves; Pipe fittings incorporating such valves with all movable sealing faces moving as one unit comprising only sliding valves, i.e. sliding closure elements with linearly sliding closure members with cylindrical slides comprising means to avoid jamming of the slide or means to modify the flow
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
    • Y10T137/00—Fluid handling
    • Y10T137/8593—Systems
    • Y10T137/86493—Multi-way valve unit
    • Y10T137/86718—Dividing into parallel flow paths with recombining
    • Y10T137/86734—With metering feature

Definitions

  • This invention relates to spool valves and, more specifically, to a spool valve in which the action of flow forces is generally constant and/or balanced for any degree of opening of the valve.
  • flow forces in spool valves and their effects have long been recognized. Depending upon the particular valve construction, its flow pattern, and the pressures involved, flow forces may tend to oppose an operator's opening the valve or act in concert therewith at widely varying values dependent upon spool travel. In some instances, for one position of the spool the flow force may oppose the operator, while in another position of the spool it may aid the operator.
  • a spool valve has a valve body with a bore intercepted by at least two axially spaced ports.
  • a spool is reciprocally received within the bore and has two axially spaced lands separated by a groove, one side wall of the groove being adjacent one of the lands and defining a shoulder.
  • a plurality of metering slots in the other land which open to the groove through the side wall thereof opposite from the first mentioned side wall, the axial length of at least two of the slots measured from the side wall opposite from the shoulder being different, and at least one additional slot is located in the shoulder and is aligned with and faces one of the metering slots. Consequently, the slots open at different points during the travel of the spool within the bore to provide a means for balancing the flow forces.
  • the additional slot preferably has a ramp-like bottom and a width different from that of the metering slot.
  • FIG. 1 is a fragmentary, sectional view of a spool valve embodying the invention
  • Fig. 2 is a fragmentary view of part of the spool of the spool valve with parts broken away for clarity;
  • Fig. 3 is a sectional view taken approximately along the line 3-3 of Fig. 2;
  • Fig. 4 is a sectional view taken approximately along the line 4-4 of Fig. 3.
  • FIG. 1 An exemplary embodiment of a spool valve is illustrated in Fig. 1 and includes a valve body 10 having a bore 12 therein.
  • a first annulus or port 14 intercepts the bore 12 and is in fluid communication with an outlet conduit 16 through which fluid received in the annulus 14 may be directed to a point of use or to reservoir.
  • annulus 18 Axially spaced along the length of the bore 12 from the annulus 14 is an annulus 18 which also intercepts the bore 12 and which is in fluid communication with a conduit 20 which will receive fluid to be metered by the valve.
  • the spool 22 includes axially spaced, lands 24 and 26 which are separated by a groove 28.
  • a side wall 30 of the groove 28 is adjacent the land 26 and defines a shoulder that is rather abrupt in nature.
  • the side wall 30 defining the shoulder is in a plane transverse (90°) to the longitudinal axis of the spool 22 and, for reasons to be seen, it is preferred that there be at least 90° between the side wall 30 and the longitudinal axis of the spool 22 measured on the side of the side wall 30 occupied by the land 26.
  • the spool 22 adjacent its opposite ends, includes seal bearing lands 34 and 36 such that the ends of the bore 12 define pressure chambers 38 and 40, respectively. Fluid under pressure may be directed to either one of the chambers 38 and 40 in any of a variety of known ways.
  • a conduit (not shown) will connect the annulus 14 to the chamber 38 while the chamber 40 will be connected to the downstream side of the usual main spool vlave (not shown) employed in a typical system.
  • the chamber 40 is also occupied by a spring 42 which abuts the right-hand end of the spool
  • the land 24 is provided with a plurality of metering slots 44, 46 and 48 which open to the groove 28. As best seen in Fig. 3, in actuality, there are two of the slots 44 diametrically opposed about the land 24, two of the slots 46, also diametrically opposed, and two of the slots 48.
  • the slots 48 are also diametrically opposed and adjacent ones of the slots 44-48 are spaced angularly by about 60°.
  • at least the slots 44 and 46 are relatively shallow so that metering will occur through an opening which is transverse to the longitudinal axis of the spool 22 and not through an opening lying in a surface of a cylinder concentric to that longitudinal axis.
  • each of the slots 44 and 46 taken transversely to the longitudinal axis of tte spool at any point along the length of the slot will be less than the area of the top of the slot (that part of the slot that would fall within the surface of the land 24 if the slot were not present) from the particular point chosen to the end of the slot remote from the groove 28.
  • the slots 44 When the spool 22 is shifted to the left, as viewed in Fig. 1, the slots 44 will first come into fluid communication with the annulus 18. Further leftward movement will bring the slots 46 into such fluid comunication as well. Finally, additional leftward movement will bring the slots 48 into such fluid communication. Because of the above-described shallow nature of at least the slots 44 and 46, the smallest opening in the flow path from the annulus 18 through the slots 44 and 46 to the annulus 14, will lie in a plane transverse to the longitudinal axis of the spool 22 with consequence that an emanating jet of fluid will be directed generally parallel to the longitudinal axis of the spool 22 toward the land 26.
  • the land 26 is provided with additional slots
  • the slots 50 and 52 opening through the shoulder defined by the side wall 30.
  • the slots 50 are aligned with the metering slots 44, while the slots 52 are aligned with the slots 46.
  • the slots 50 and 52 provide exiting ramps for the jet streams of fluid emanating from the slots 44 and 46 into the annulus 14.
  • the bottoms of the slots 50 and 52 are designated 54 and are generally planar in a plane non- parallel to the longitudinal axis of the spool 22. Since the formation of perfectly planar bottoms 54 may be difficult, from a manufacturing standpoint, they may be formed of two or more arcuate sections 56 and 58 (Fig. 2 as would result from two arcuate cuttings utilizing, for example, a Woodruff key cutter at different centers.
  • the widths of at least some of the metering slots, such as the metering slots 44 differ from the widths of the corresponding, aligned, additional slots such as the slots 50.
  • the additional slots 50 are wider than the aligned metering slots 44.
  • the additional slots may have a lesser width than the aligned metering slots. Relative width selection can be based on desired characteristics by those skilled in the art with the knowledge of how the width affects operation, as will be described.
  • the loading of the spring and the pressure drop across the metering orifice affect the total forces applied to the spool.
  • a spring such as the spring 42 extends
  • the spring force will fall off at a substantially linear rate.
  • the pressure drop across the metering orifice will also change.
  • the pressure drop will become smaller, although not in proportion to the size of the metering orifice.
  • the pressure drop may stay relatively constant over a spool travel providing partial flow to a point whereat full flow begins to occur. Thereafter, full flow may be maintained while the pressure will drop.
  • the metering slots 44 will first be cracked and a large pressure drop will occur, with the consequence that a very high velocity jet stream of fluid will be directed substantially parallel to the longitudinal axis of the spool 22. Because of the smallness of the orifice, the width of the jet stream will be relatively small and the entire stream may exit into the annulus 14 through the additional slot 50. Because of the inclination of the bottom 54 of the slot 50, very little force will be exerted against the land 26 due to the stream of fluid at this time. Consequently, flow forces will be essentially those provided by the reaction of the fluid entering the slot 44 from the annulus 18 as a reactive force against the bottom of the slot 44. This force will aid that supplied by the spring 42.
  • the metering orifice will increase in size, with the consequence that the jet stream of fluid emanating therefrom will become wider and a portion thereof will begin to impinge on the shoulder defined by the groove side 30.
  • a force will be generated caused by fluid striking the shoulder 30, which force will be in opposition to that provided by the spring 42 and which will counterbalance an increasing flow force caused by the reaction of fluid against the bottom of the metering slot 44 so that the net force due to flow forces remain substantially constant.
  • the width of the additional slots 50 and 52 affects the degree to which a force opposing the spring 40 is generated by fluid impinging upon the shoulder 30. The wider the additional slots 50 and 52, the less spring opposing force is generated by such impingement.
  • a spool valve made according to the invention balances flow forces. When made with a plurality of slots having differing axial lengths, the ability to achieve such a balance over an extremely wide range of spool positions is provided. It will also be recognized that by pairing slots of equal axial length on opposite sides of the spool, equal forcqs will be present on both sides thereof to prevent any tendency of the spool 22 to cant and bind. If desired, the shoulder 30 may be formed with a negative angle to provide a greater barrier for fluid emanating from the metering slots where a greater spring opposing force is desired. And, by varying the widths of the additional slots 50 and 52, the effectiveness of the shoulder 30 as a barrier can be controlled to achieve any desired characteristic in a valve.
  • slot is not restricted to configurations such as those illustrated in the drawings, but may include, by way of example, drilled passages, grooves, etc.

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  • Engineering & Computer Science (AREA)
  • General Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Sliding Valves (AREA)
  • Multiple-Way Valves (AREA)

Abstract

A spool valve in which the action of flow forces is balanced for any degree of opening of the valve. In spool valves, flow forces may tend to oppose an operator's actuation of the valve or in some positions act in the same direction as the operator's actuation, making precise control of fluid flow difficult. This invention solves this problem since, with fluid forces balanced, the control force provided by the operator is the sole determinant of spool position. The spool valve includes a valve body (10) having a bore (12) intercepted by at least two axially spaced ports (16, 20) and a spool (22) reciprocally received within the bore and having two axially spaced lands (24, 26) separated by a groove (28), one side wall (30) of the groove being adjacent one of the lands and defining a shoulder. At least one shallow metering slot (44) is disposed in the other of the lands and opens to the groove through another side wall thereof opposite from the first mentioned side wall. The slot has an increasing depth in the direction toward the groove and a cross sectional area taken transversely to the axis of the spool at any point along the slot less than the area of the top of the slot from the point to the end of the slot remote from the groove. An additional slot (50) is disposed in the shoulder and opens to the groove and has a ramp-like bottom and a width different from that of the metering slot.

Description

Description
FLOW FORCE BALANCED SPOOL VALVE
Technical Field
This invention relates to spool valves and, more specifically, to a spool valve in which the action of flow forces is generally constant and/or balanced for any degree of opening of the valve.
Background Art
The existence of flow forces in spool valves and their effects have long been recognized. Depending upon the particular valve construction, its flow pattern, and the pressures involved, flow forces may tend to oppose an operator's opening the valve or act in concert therewith at widely varying values dependent upon spool travel. In some instances, for one position of the spool the flow force may oppose the operator, while in another position of the spool it may aid the operator.
Consequently, precise control of the flow of fluid may be difficult to achieve to the desired degree because spool position will not be solely determined by a control force provided by an operator for the valve. When the flow force is assisting the operator force, the total force operating on the spool will be greater than that provided by the operator alone and the total force may vary according to spool position. The same is true when the flow forces are acting in opposition to the operator force and, of course, when flow forces can act both in concert arid in opposition to the operator force, dependent upon spool travel, accurate placement of the spool through operator force at all positions along the path of travel of the spool becomes exceedingly difficult to attain. Therefore, there is a need for a spool valve wherein flow forces are substantially balanced and/or constant throughout the operating parameters of the valve.
Examples of balanced spool valves are disclosed in U. S. Patents 2,747,612, issued to Lee on May 29, 1956; 3,198,212 issued to Junck et al on August 3, 1965; and 3,990,477, issued to Johnson on November 9 , 1976.
Disclosure of the Invention
The present invention is directed to overcoming one or more of the above problems. In the illustrated embodiment, a spool valve has a valve body with a bore intercepted by at least two axially spaced ports. A spool is reciprocally received within the bore and has two axially spaced lands separated by a groove, one side wall of the groove being adjacent one of the lands and defining a shoulder.
In one aspect of the invention, there are provided a plurality of metering slots in the other land which open to the groove through the side wall thereof opposite from the first mentioned side wall, the axial length of at least two of the slots measured from the side wall opposite from the shoulder being different, and at least one additional slot is located in the shoulder and is aligned with and faces one of the metering slots. Consequently, the slots open at different points during the travel of the spool within the bore to provide a means for balancing the flow forces.
In another aspect of the invention, there is provided at. least one shallow metering slot in the other of the lands, as identified above, and opening to the groove through the side wall, opposite the shoulder; the slot having an increasing depth in the direction toward the groove and a cross sectional area taken transversely to the axis of the spool at any point along the slot less than the area of the top of the slot from that point to the end of the slot remote from the groove; and an additional slot in the shoulder and opening to the groove. The additional slot preferably has a ramp-like bottom and a width different from that of the metering slot.
Other features and advantages will become apparent from the following specification taken in connection with the accompanying drawings.
Brief Description of the Drawings Fig 1 is a fragmentary, sectional view of a spool valve embodying the invention;
Fig. 2 is a fragmentary view of part of the spool of the spool valve with parts broken away for clarity; Fig. 3 is a sectional view taken approximately along the line 3-3 of Fig. 2; and
Fig. 4 is a sectional view taken approximately along the line 4-4 of Fig. 3.
Best Mode For Carrying Out The Invention An exemplary embodiment of a spool valve is illustrated in Fig. 1 and includes a valve body 10 having a bore 12 therein. A first annulus or port 14 intercepts the bore 12 and is in fluid communication with an outlet conduit 16 through which fluid received in the annulus 14 may be directed to a point of use or to reservoir.
Axially spaced along the length of the bore 12 from the annulus 14 is an annulus 18 which also intercepts the bore 12 and which is in fluid communication with a conduit 20 which will receive fluid to be metered by the valve.
Reciprocally received within the bore 12 is a spool 22. The spool 22 includes axially spaced, lands 24 and 26 which are separated by a groove 28. A side wall 30 of the groove 28 is adjacent the land 26 and defines a shoulder that is rather abrupt in nature. As seen in Fig. 1, the side wall 30 defining the shoulder is in a plane transverse (90°) to the longitudinal axis of the spool 22 and, for reasons to be seen, it is preferred that there be at least 90° between the side wall 30 and the longitudinal axis of the spool 22 measured on the side of the side wall 30 occupied by the land 26. The spool 22, adjacent its opposite ends, includes seal bearing lands 34 and 36 such that the ends of the bore 12 define pressure chambers 38 and 40, respectively. Fluid under pressure may be directed to either one of the chambers 38 and 40 in any of a variety of known ways. For example, when the valve is employed as a flow control valve, a conduit (not shown) will connect the annulus 14 to the chamber 38 while the chamber 40 will be connected to the downstream side of the usual main spool vlave (not shown) employed in a typical system. The chamber 40 is also occupied by a spring 42 which abuts the right-hand end of the spool
22 to bias the same towards the left, as viewed in Fig. 1.
The land 24 is provided with a plurality of metering slots 44, 46 and 48 which open to the groove 28. As best seen in Fig. 3, in actuality, there are two of the slots 44 diametrically opposed about the land 24, two of the slots 46, also diametrically opposed, and two of the slots 48. The slots 48 are also diametrically opposed and adjacent ones of the slots 44-48 are spaced angularly by about 60°. In a preferred embodiment, at least the slots 44 and 46 are relatively shallow so that metering will occur through an opening which is transverse to the longitudinal axis of the spool 22 and not through an opening lying in a surface of a cylinder concentric to that longitudinal axis. In other words, the cross sectional area of each of the slots 44 and 46 taken transversely to the longitudinal axis of tte spool at any point along the length of the slot will be less than the area of the top of the slot (that part of the slot that would fall within the surface of the land 24 if the slot were not present) from the particular point chosen to the end of the slot remote from the groove 28.
It will also be observed that all of the slots 44-48 have an increasing depth on the direction toward the groove 28.
When the spool 22 is shifted to the left, as viewed in Fig. 1, the slots 44 will first come into fluid communication with the annulus 18. Further leftward movement will bring the slots 46 into such fluid comunication as well. Finally, additional leftward movement will bring the slots 48 into such fluid communication. Because of the above-described shallow nature of at least the slots 44 and 46, the smallest opening in the flow path from the annulus 18 through the slots 44 and 46 to the annulus 14, will lie in a plane transverse to the longitudinal axis of the spool 22 with consequence that an emanating jet of fluid will be directed generally parallel to the longitudinal axis of the spool 22 toward the land 26. The land 26 is provided with additional slots
50 and 52 opening through the shoulder defined by the side wall 30. The slots 50 are aligned with the metering slots 44, while the slots 52 are aligned with the slots 46. The slots 50 and 52 provide exiting ramps for the jet streams of fluid emanating from the slots 44 and 46 into the annulus 14. The bottoms of the slots 50 and 52 are designated 54 and are generally planar in a plane non- parallel to the longitudinal axis of the spool 22. Since the formation of perfectly planar bottoms 54 may be difficult, from a manufacturing standpoint, they may be formed of two or more arcuate sections 56 and 58 (Fig. 2 as would result from two arcuate cuttings utilizing, for example, a Woodruff key cutter at different centers.
As can be seen from a comparison of Figs. 3 and 4, the widths of at least some of the metering slots, such as the metering slots 44, differ from the widths of the corresponding, aligned, additional slots such as the slots 50. For example, as illustrated in the drawings, the additional slots 50 are wider than the aligned metering slots 44. In general, such dimensioning is desirable but instances will occur where the metering slots and the additional slots aligned therewith will have the same width. And, in some instances, the additional slots may have a lesser width than the aligned metering slots. Relative width selection can be based on desired characteristics by those skilled in the art with the knowledge of how the width affects operation, as will be described.
In a typical prior art spool valve utilizing metering slots, the loading of the spring and the pressure drop across the metering orifice affect the total forces applied to the spool. As a spring, such as the spring 42 extends, the spring force will fall off at a substantially linear rate. The pressure drop across the metering orifice will also change. As the metering orifice opens, the pressure drop will become smaller, although not in proportion to the size of the metering orifice. For example, the pressure drop may stay relatively constant over a spool travel providing partial flow to a point whereat full flow begins to occur. Thereafter, full flow may be maintained while the pressure will drop.
As the valve 22 is moved towards the left, as viewed in Fig. 1, the metering slots 44 will first be cracked and a large pressure drop will occur, with the consequence that a very high velocity jet stream of fluid will be directed substantially parallel to the longitudinal axis of the spool 22. Because of the smallness of the orifice, the width of the jet stream will be relatively small and the entire stream may exit into the annulus 14 through the additional slot 50. Because of the inclination of the bottom 54 of the slot 50, very little force will be exerted against the land 26 due to the stream of fluid at this time. Consequently, flow forces will be essentially those provided by the reaction of the fluid entering the slot 44 from the annulus 18 as a reactive force against the bottom of the slot 44. This force will aid that supplied by the spring 42.
As more and more of the metering slot 44 is exposed, the metering orifice will increase in size, with the consequence that the jet stream of fluid emanating therefrom will become wider and a portion thereof will begin to impinge on the shoulder defined by the groove side 30. As a result, a force will be generated caused by fluid striking the shoulder 30, which force will be in opposition to that provided by the spring 42 and which will counterbalance an increasing flow force caused by the reaction of fluid against the bottom of the metering slot 44 so that the net force due to flow forces remain substantially constant. By providing a series of slots, such as the slots 44,46 and 48, all having differing axial lengths, the ability to balance flow forces at a variety of differing spool positions is achieved. The width of the additional slots 50 and 52 affects the degree to which a force opposing the spring 40 is generated by fluid impinging upon the shoulder 30. The wider the additional slots 50 and 52, the less spring opposing force is generated by such impingement.
A spool valve made according to the invention balances flow forces. When made with a plurality of slots having differing axial lengths, the ability to achieve such a balance over an extremely wide range of spool positions is provided. It will also be recognized that by pairing slots of equal axial length on opposite sides of the spool, equal forcqs will be present on both sides thereof to prevent any tendency of the spool 22 to cant and bind. If desired, the shoulder 30 may be formed with a negative angle to provide a greater barrier for fluid emanating from the metering slots where a greater spring opposing force is desired. And, by varying the widths of the additional slots 50 and 52, the effectiveness of the shoulder 30 as a barrier can be controlled to achieve any desired characteristic in a valve.
Finally, as used herein, the term "slot" is not restricted to configurations such as those illustrated in the drawings, but may include, by way of example, drilled passages, grooves, etc.

Claims

Claims
1. A spool valve comprising: a valve body (10) having a bore (12) intercepted by at least two axially spaced ports (14 ,18) ; a spool (22) reciprocally received within said bore and having two axially spaced lands (24,26) separated by a groove (28) pne side wall (30) of said groove being adjacent one of skid lands and defining a shoulder; a plurality of metering slots (44,46,48) in the other of said lands and opening to said groove through another side wall thereof opposite said one side wall, the axial length of at least two of said slots measured from said another side wall being different; and a least one additional slot (50,52) in said shoulder and aligned with and facing one of said metering slots.
2. The spool valve of claim 1 wherein said additional slot has a bottom (54) configured as a substantially planar ramp nonparallel to the longitudinal axis of said spool.
3. The spool valve of claim 1 wherein said additional slot has a width different than the width of the metering slot with which it is aligned.
4. The spool valve of claim 1 wherein said additional slot has a bottom (54) configured as a substantially planar ramp nonparallel to the longitudinal axis of said spool and a width somewhat greater than the width of the metering slot with which it is aligned.
5. The spool valve of claim 1 wherein said shoulder is a surface at at least about 90° to the longitudinal axis of said spool measured from the side thereof including said one land.
6. A spool valve comprising: a valve body (10) having a bore (12) intercepted by at least two axially spaced ports (14,18); a spool (22) reciprocally received within said bore and having two axially spaced lands (24,26) separated by a groove (28), one side wall (30) of said groove being adjacent one of said lands and defining a shoulder; at least one shallow metering slot (44,46) in the other of said lands and opening to said groove through another side wall thereof opposite said one side wall, said slot having an increasing depth in the direction toward said groove and a cross sectional area taken transversely to the axis of said spool at any point along said slot less than the area of the top of the slot from said any point to the end of the slot remote from said groove; and an additional slot (50,52) in said shoulder opening to said groove and having a ramp-like bottom (54) .
7. A spool valve according to claim 6 wherein the additional slot (50,52) has a width different from that of said metering slot.
8. A spool valve according to claim 7 wherein said bottom is approximately planar and defined by at least two arcuate machined cuts (56,58) having different centers.
9. A spool valve according to claim 7 wherein said additional slot is wider than said metering slot and wherein said shoulder is abrupt.
10. A spool valve comprising: a valve body (10) having a bore (12) intercepted by at least two axially spaced ports (14,18); a spool (22) reciprocally received within said bore and having two axially spaced lands (24,26) separated by a groove (28) one side wall (30, of said groove being adjacent one of said lands and defining a shoulder; a plurality of metering slots (44,46,48.) in the other of said lands and opening to said groove through another side wall thereof opposite said one side wall, the axial length of at least two of said slots measured from said another side wall being different; at least one of said metering slots (44,46) having an increasing depth in the direction toward said groove and a cross sectional area taken transversely to the axis of said spool at any point along said one slot less than the area of the top of said one slot from said any point to the end of the slot remote from said groove; and at least one additional slot (50,52) in said shoulder and aligned with and facing said one metering slot and having a width greater than that of said one metering slot.
PCT/US1979/000193 1978-04-19 1979-03-26 Flow force balanced spool valve Ceased WO1979000947A1 (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
DE7979900423T DE2964586D1 (en) 1978-04-19 1979-03-26 Flow force balanced spool valve

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US897894 1978-04-19
US05/897,894 US4245816A (en) 1978-04-19 1978-04-19 Flow force balanced spool valve

Publications (1)

Publication Number Publication Date
WO1979000947A1 true WO1979000947A1 (en) 1979-11-15

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Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US1979/000193 Ceased WO1979000947A1 (en) 1978-04-19 1979-03-26 Flow force balanced spool valve

Country Status (7)

Country Link
US (1) US4245816A (en)
EP (1) EP0015955B1 (en)
JP (1) JPS55500277A (en)
BE (1) BE875092A (en)
CA (1) CA1109359A (en)
DE (1) DE2964586D1 (en)
WO (1) WO1979000947A1 (en)

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EP0391332A3 (en) * 1989-04-04 1991-11-06 Aisin Seiki Kabushiki Kaisha Pressure control valve device
AU2016392763B2 (en) * 2016-05-31 2018-12-13 Komatsu Ltd. Spool valve, operation device, and work vehicle

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US4694649A (en) * 1983-02-04 1987-09-22 Howeth David F Pressure limiting acceleration control system and valve for hydraulic motors
US4526000A (en) * 1983-10-18 1985-07-02 Mccartney Manufacturing Co., Inc. Pressure intensifier
US4667930A (en) * 1986-06-09 1987-05-26 Caterpillar Inc. Metering slot configuration for a valve spool
GB8717963D0 (en) * 1987-07-29 1987-09-03 Vickers Systems Ltd Spool
US5271430A (en) * 1988-08-16 1993-12-21 Kabushiki Kaisha Komatsu Seisakusho Flow rate control valve device and flow force reduction structure
US4941508A (en) * 1989-12-28 1990-07-17 Dana Corporation Force balanced hydraulic spool valve
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AU2016392763B2 (en) * 2016-05-31 2018-12-13 Komatsu Ltd. Spool valve, operation device, and work vehicle
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Also Published As

Publication number Publication date
EP0015955A1 (en) 1980-10-01
BE875092A (en) 1979-09-26
CA1109359A (en) 1981-09-22
EP0015955B1 (en) 1983-01-26
DE2964586D1 (en) 1983-03-03
JPS55500277A (en) 1980-05-08
US4245816A (en) 1981-01-20

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